空载变压器受电时引起励磁涌流的原因是（）。
A、线圈对地电容充电
B、合闸于电压最大值
C、铁芯磁通饱和
D、不是上述原因
参考答案：C
The phenomenon that words having different meanings have the same form is called ______.
A. hyponymy B. synonymy C. polysemy D. homonymy
正方形有[ ]
A．3条边
B．4条边
C．条边
